The invention pertains to a measuring circuit, in particular, an ASIC for current, voltage and temperature measurements (e.g., in an on-board network of a motor vehicle) according to the preamble of claim 1.
Commonly invented EP 1 030 185 A2 and U.S. Pat. No. 6,489,693 B1 disclose a measuring circuit in the form of an ASIC (Application-Specific Integrated Circuit), which monitors the current in the on-board network of a motor vehicle in order to identify defective loads or to detect a battery overload.
So-called chopper amplifiers, among other devices, are used for measuring analog signals. These chopper amplifiers make it possible to reduce the input voltage offset and its temperature drift, as well as low-frequency noise. Chopper amplifiers of this type consist of a chopper on the input side, a downstream amplifier, and a demodulator on the output side which rectifies the chopped and amplified measuring signal phase-synchronously.
The disadvantages of known chopper amplifier circuits can be seen in the unsatisfactory noise behavior, the incomplete suppression of the input offset voltage and the fact that these circuits are only available in the form of separate amplifier circuits.